Expansible oven strip processing means



y 1962 A. v. ALEXEFF E'IAL 3,045,360

EXPANSIBLE OVEN STRIP PROCESSING MEANS 5 Sheets-Sheet 1 Filed July 21, 1959 REVERSIBLE 45 MOTOR VARIABLE SPEED D. C. MOTOR D. C. MOTOR 6 2 lIlll I I I I I I I I II 6 E m 2 ED 0% E R I I I I III III V P EW 8 V PE 2 SR fifi/s 2 7 2g! 51 I w R D mv 9 U 2/ SR W E T L 0 $0M IE R EC V SE R me D w W 2..I 2 SR III I I I I T 2 7 4 2 mxA NEH EM W M MB A, R Wm H E H W C E G A mm mm mm w L R M L CAB 9% TN A 6 2 5 w 6 MOTOR GENERATOR FIELD ATTORNEYS July 24, 1962 A. v. ALEXEFF ETAL 3,045,360

EXPANSIBLE OVEN STRIP PROCESSING MEANS 5 Sheets-Sheet 3 Filed July 21, 1959 [lg-roll "strip ref f roll eXposuresfrip ref eXposureroll srrip ef roll - exposure|- sfrip refD roll trunsienr -"exposure|-- ATTORNEYS nit-ed tates Patent 3,045,360 EXPANSIBLE OVEN STRIP PROCESSING MEANS Alexander V. Alexetf, Cleveland, and Howard R. Richards, Lakewood, Ohio, assignors to Industrial Ovens, Incorporated, Cleveland, Ohio, a corporation of Ohio Filed July 21, 1959, Ser. N 828,647

8 Claims. (Cl. 3452) This invention relates to line processing of webs and strands and particularly to means for attaining uniformity of exposure of the material undergoing treatment within a treating chamber during transients in line v velocity. For purposes of this application, strands is to be understood to include monofilaments such as nylon, rayon, and glass fiber as wellas wires, cords, narrow tapes and tubings, and strips is to be understood to include strands and also Webs such as metal sheet, paper, textiles, films and wide tapes.

In many present day continuous or semi-continuous strip treating applications, it is desirable to maintain a high degree of uniformity of treatment of the strip from increment to increment of its length. This is particularly desirable where the treatment can be wholly satisfactory only when carried out Within narrow critical ranges of conditions.

A purpose of the present invention is to provide for a high degree of uniformity under transient conditions, particularly under conditions where web speed is changed atsuch a rate as to significantly disturb the uniformity of exposure from increment to increment of the length of the strip in the vicinity of treating chamber during the change in Web speed.

The invention so relates the movement of strip guiding means within the treating chamber to changes in strip speed as to achieve uniformity of exposure of every increment of strip length. The invention involves the concept of translating the strip guiding means in a path in the chamber to vary the instantaneous length of strip material within the chamber, and slaving velocity of the guiding means to the increasing change in velocity of the strip during the shorter ,of desired exposure time and strip speed transient time, then continuing strip guiding means translation at attained velocity until the longer of such two times expires, and then reducing the velocity of the strip guiding means as a function of time symmetrical to the time-function of velocity increase of the strip guiding means which has just occurred. a

The invention may also be viewed as embodying the concept of slaving translation velocities of the web guiding means with reference to and as a direct proportion of the differential between instantaneous strip velocity on the one hand and on the other hand reference velocities established by a suitable speed reference means, which reference means is adapted at the beginning of a strip speed transient to indicate the previously-established strip velocity which is being departed from and which reference means, after an interval equal to the desired strip exposure time variation, indicates reference velocity as a time-function'reversely profiled to the time-function of the'preceding departures of strip velocity from indicated reference velocities.

The objects and advantages of the invention will become apparent from the following description of specific "ice embodiments of the invention. As will be apparent to those familiar'with strip processing, specific mechanical, electrical or hydraulic control components to be employed in any given installation may be a matter of choice. Suitable apparatus in each illustrated embodiment is therefore illustrated'schematically and is separated into given components for given functions to an extent greater than necessary rather than being illustrated as integrated multiple-function components, all this being done in the interest of clarity in order that the invention maybe most concisely and completely disclosed and understood.

In the drawings:

FIGURE 1 is a partly schematic and partly diagrammatic illustration of a semi-continuous strip processing system embodying the invention.

FIGURE 2 is a similar illustration of another embodimentof the invention in a semi-continuous strip processing system.

The remainderof the figures, starting with FIGURE 3A and ending With'FIGURE 63, illustrates in graphic form certain velocity-time functions and accelerationtime functions which are of significance in the description of the invention.

FIGURE 1 illustrates a semi-continuous installation in which the invention is employed. The illustrated installation might be employed in connection with dip-coating a Web, the Web then being heated, dried and simultaneously stretched under. considerable tension. In applications of this type, it is frequently important to maintain a uniformity of treatment of increments of the web length and to maintain treating conditions as constant as possible from increment to increment of the strip length. In the illustration, the strip comprises a Web 10.

Components of the installation shown in FIGURE 1 include a let-off stand 11; a dip station 13; a first pull roll stand 14; a treating chamber indicated generally by the reference numeral 15, which might for example be a heating chamber; a complementary treating chamber 16, which in many applications will not be employed but which in the illustrated application may be provided and may constitute a cooling tower; a web-length-sensing stand .17; a second pull roll stand 18; and a Wind-up stand 19.

The installation may employ, in any conventional manner, a plurality of variable speed DC. motors as a power and control means for the several web driving members. The power and control system may comprise a motor 20; a generator 21; a field exciter 22; an overriding or governing speed control rheostat 23.; and a plurality of voltage-responsive, variable speed DC motors 24, 25 and 26, each of these motors with the exception of the motor 24 being provided with its own subsidiary speed control means such as field voltage rheostats 27, such subsidiary speed control means being responsive to variation in length between severalpoints in the system as explained below. Speed reducers 28 are associated with each of the motors 24--26 and also with an additional motor 29 which is not provided with its own subsidiary field voltage rheostat but which is provided with a speed control rheostat 30 parallel to the rheostat 23 and adapted to govern the speed of the motor 29 as a function of the adjustment of the rheostat 30 which is exactly the same as the function by which the control of the speed 3 of the motor 24 is governed by adjustment of the rheo stat 23.

The treating chamber 15 may be constructed and arranged so that both entrance and egress of the web occurs through the port 42 during normal operation, the web being guided into and out of the port by the rolls 41. Within the chamber 15, the web passes around web guiding means comprising in this instance a single dancer roll 40. The dancer roll 40 is mounted for lateral displacement so that it may be shifted up and down in a vertical path within the treating chamber and may, furthermore, be translated a sufficient extent to pass completely, or at least partially, out through the port 42. For this purpose, the ends of the dancer roll 40 may be mounted in blocks which are engaged by an endless cable or chain 43 at either side of the oven. Each cable or chain 43 passes around associated sprockets or sheaves 44, one of which is powered by a reversible motor 45 through a speed reducer 48. The motor 45 is controlled by an on-olf and reversing switch 46. The speed reducer 48 is connected to its associated sheave 44 through a one-way clutch or torque transmitter 47, i.e., a clutch adapted to transmit torque in either rotative direction but only in the axial direction from right to left as seen in FIGURE 1, application of torque in the opposite axial direction resulting in uncoupling or disengagement of the clutch 47. The result is that the dancer roll 40 may be moved up and down by additional means to be described below without being braked by the speed reducer 48 or the motor 45 when the motor 45 is not running.

Means for slaving motion of the dancer roll 40 to transients in web motion are provided which in the i1- lustrated apparatus includes a differential linkage 50 with inputs from the output shafts of the speed reducers associated with the motors 24 and 29 and with an output 51 tying through a friction connection 52 to a drive for one of the sprockets or sheaves 44. The friction connection 52 is such that it may be overcome by actuation of the dancer roll 40 by the motor 45, but any new angular relationship thereby established between the differential output shaft 51 and the associated sheave 44 will remain established upon cessation of translation of the dancer roll 40 by the motor 45 to thereby establish a new datum position for the roll 40 from which it will move upon subsequent actuation of the output shaft 51 of the differential 50.

It will thus be understood that the output shaft 51 will rotate at a rate proportional to the difference between the rate of rotation of the outputs of the speed reducers associated with the motors 24 and 29. In the illustrated apparatus, the rate of rotation of the output 51 will be half the difference between the rates of rotation of the input shafts.

It will be understood that electronic sensing and control means may be provided instead of the mechanical linkages of the types disclosed, which are set forth for the purpose of most clearly illustrating the invention. As previously mentioned, the speed of the motor 29 is governed by the position of the rheostat 30 which controls armature voltage and which is connected in parallel with the armature voltage controlling rheostat 23 for the motor 24 or is connected in any other way such that the difference between the speeds of the two inputs to the differential 50 will be proportional to the angular difference in position between the control arms of the rheostats 23 and 30.

There is provided a timing and transient controlling linkage including a reversible variable speed motor 55 which may be set for a given speed of rotation in either direction by a suitable control 56. The motor 55, through a speed reducer 57, drives output shafts 58 at identical, although adjustable, speeds of rotation. One of the shafts 58 is connected to a shaft 59 governing the angular position of the rheostat control arm of the rheostat 23. This connection to the shaft 59 is effected through a clutchand-brake device 60 of the type adapted to substantially instantaneously brake the shaft 59 to a complete stop in one position and to substantially instantaneously couple the shaft 59 to the associated shaft 58 for rotation therewith (without appreciable braking of the motor 55) when the device 60 is in the opposite position. The device 60 is moved to clutch-engaging position by closing of a timing switch 61 and is moved to brake-engaging position by opening of the timing switch 61.

The other of the shafts 58 is connected to a shaft 62 governing the angular position of the rheostat control arm of the rheostat 38. This connection to the shaft 62 is effected through a clutch-and-brake device 63 similar to the clutch-and brake device 60. The device 63 is moved to clutch-engaging position by closing of a timing switch 64 and to brake-engaging position by opening of the timing swtich 64. The time interval of the timing switch 64 is set by a control knob 65, and the switches 64 and 61 are tied together as by a shaft 70 so that setting of the timing switch 64 for a given timing interval also results in setting of the timing switch 61 for the same timing interval. The timing switches 61 and 64 are supplied from a line 66 as by closing of a switch 67. Between the switch 67 and the timing switch 64 is inserted a time delay switch 68 having a control knob 69 for varying the time delay interval thereof. The result is that when the switch 67 is closed, current is immediately applied to the timing switch 61 which closes for the pre-set interval and then opens. After the time delay established by the time delay switch 68, the timing switch 64 also closes for the identical pre-set interval and then opens.

During the time the switch 61 is closed, the position of the control arm of the rheostat 23 is changed at a rate and in a direction determined by the rate of rotation and directional setting of the control 56 associated with the motor 55. The identical movement occurs in connection with the control arm 30 but at a later time interval, the start of which is determined by the pre-set time delay interval of the switch 68.

It will be apparent that the speed of the motor 55 will govern the rate of change of angular positions of the control arms of the rheostats 23 and 30 and will therefore govern the rate of acceleration of the outputs associated with the motors 24 and 29. Since the shaft 51 rotates at a speed which is one-half the difierence in speed between the outputs of the speed reducers 28 associated with the motors 24 and 29, it will be understood that the shaft 51 accelerates at one-half the rate of acceleration of the differential input shaft powered by the motor 24 during such time as the motor 29 maintains a constant speed of rotation and that the shaft 51 accelerates in an algebraically negative direction (decelerates) at one-half the rate of acceleration of the differential input shaft powered by the motor 29 when the motor 24 maintains a constant speed of rotation. It will also be clear that the shaft 51 rotates at a constant speed (zero acceleration) when the motors 24 and 29 are operating at different speeds but are accelerating or decelerating at the same rate. Accordingly, it will be seen that translation velocity of the roll 40 in its vertical path within the treating chamber 15 is responsively varied with reference to the amount of and sign of departure of the speed of the motor 24 (and velocity of the web 10) from the reference velocities indicated by the reference means comprising the output of the motor 29 and speed reducer 28, and as a direct proportion of such departure. It may be assumed in the specific apparatus illustrated that the effective diameter of the powered roll 72 in the pull roll stand 14 is the same as the effective diameter of the drive sheave 44 which is powered by the differential output shaft 51.

When the web processing line is started up and attains a given velocity, the switch 46 is manually closed to move the position of the dancer roll 46 to a desired height so as to establish a desired exposure time Within the treating chamber for the given web velocity. The switch 46 is then opened. Now, if it is desired to change web speed without changing exposure time for any increment of the passing web, the speed control 56 of the motor 55 is adjusted to determine the rate of acceleration or deceleration, the rotational direction chosen determining whether there shall :occur acceleration or deceleration. A suitable dial associated with the control 56 may be calibrated to indicate the speed of motor 55 and therefore the rate of acceleration or deceleration of the line. The new line speed to be attained may then be chosen by adjusting the control 65 to pro-set the time during which the change in web speed will occur. Determination of this time interval together with the determination of the rate of acceleration or deceleration will, of course, preestablishthe new line speed. The control 69 for the switch 68 is preset to the desired exposure time which theweb is .already experiencing within the chamber 15.

When these settings have been made and when the transient is to be started, the switch 67 is closed. Immediately, the control arm of the rheostat 23 moves at a rate determined by the speed of the motor 55 causing the line to accelerate at the desired rate and for the desired time. At the end of such time of acceleration, the switch 61 opens and the control arm of the rheostat 23 instantaneously stops.

Meanwhile, the switch 68 closes after a time interval equal to strip exposure time within the chamber '15, and the reference velocity indicated by the output of the motor 29 thereupon begins to change as a time-function reversely profiled to that of the departure of strip velocities.

The reverse profiling above-mentioned has reference to a relationship between two velocity-time curves such that they extend between the same velocity limits and also such that associated curves representing the differentials of the velocity-time curves with respect to time are symmetrical about an axis at the midpoint in time between the time extremes of the velocity-transient portions of such ve1ocity-time curves. I

The curves shown in FIGURES 3A and 33 represent, respectively, velocity-time functions and acceleration-time functions for the operations of the apparatus as above described during an increase in line Velocity and in the case when time of exposure within the treating chamber exceeds the time interval during which the line changes velocity.

FIGURES 4A and 4B represent, respectively, these functions when the time interval during which the line changes velocity exceeds the exposure time of the strip within the treating chamber.

The curves showing strip velocity (v and reference velocity (v in FIGURES 3A and 4A are reversely profiled with respect to each other. The reverse profiling is established because the curves v and r extend between the same velocity limits and it is seen in FIGURES 3B and 4B that the strip acceleration (a and the acceleration of the reference means (a are symmetrical about an axis at the midpoint in time between the time extremes of the curves v and 11 v The curves v and v in FIGURES 3A and 4A are special cases of reverse profiling, since they are not only reversely profiled with respect to each other as above described, but their velocitytransient portions are parallel to each other. In its broadest aspects the scope of the invention is not limited to such a parallelism. For example, FIGURES 5A and 5B represent, respectively, velocity-time functions and acceleration-time functions for the operation of hydraulically, mechanically, or electronically controlled apparatus in which strip acceleration varies during velocity transient. FIGURES 5A and 5B relate to a situation where desired exposure time within the treating chamber exceeds desired time of strip-velocity g transient. FIGURES 6A and 6B are generally similar to FIGURES 5A and 5B but represent the curves where time of web-velocity transient is greater than time of exposure within the treating chamber.

The relationship between the curves v and v in both FIGURES 5A and 6A will be seen to be a relationship of reverse profiling as above described. These curves represent a somewhat more general case of reverse profiling than that illustrated in FIGURES 3A and 4A. Again it will be seen that they extend between the same velocity limits. Again it will be seen from the associated FIGURES 5B and 6B that the strip acceleration (a and the acceleration of the reference means (a are symmetrical about an axis at the midpoint in time between the time extremes of the curves v and v It will be understood from the above discussion that the relationship of the motion of the guide roll'means to web velocity transients may also be defined in the following terms: Inward (upward) or outward (downward) translation of the dancer roll 40 is slaved to positive and negative acceleration, respectively, of the strip, and instantaneous translation velocity of the dancer roll in such directions occurs as a direct proportion of the instantaneous departure of strip velocity from the strip velocity prior to the transient until there has elapsed following initiation of strip acceleration the shorter of (1) the exposure time within the treating chamber 15 and (2) the strip velocity transient time, and dancer translation then continues at constant velocity until the longer of intervals (1) and (2) above expires, and finally velocity of the dancer roll is varied to decrease the velocity as a function of time symmetrical to the time-function according to which it has just been increased.

In the following'discussion, it has been assumed, as has been the case in practice up to the present time, that the diameter of the dancer roll is an insignificant factor.

FIGURE 2 illustrates a strip processing line which is in general similar to that illustrated in FIGURE 1-, with iike reference numerals indicating like elements. FIG- URE 2 is intended to illustrate some desirable features which may be employed in a strip processing line embodying the invention.

There is'shown in FIGURE 2, a DC. tachometer bridge 80 sensing the difference in rotational speed be tween the outputs of the speed reducers associated with motors 24 and 25. Since constant tension is maintained on the length of strip between the corresponding pull roll stands 14 and 18 :by the weight ;W at the stand 17, such differences in rotational speed are a measure of the amount of stretch occurring between such pull roll stands. The output signal from the DC. tachometer bridge 80 may be fed through line 81 and through control potentiorneter 82 which controls the motor 45 in substitution for the manuaily operated switch 46 of FIGURE 1. Accordingly, the position of the dancer roll 40 will be varied in such a direction to slightly increase exposure time within the chamber 15 upon a sensed decrease in web stretch or to slightly decrease exposure time within the chamber 15 upon a sensed increase in web stretch. It will be understood that if this feedback control is operating, it will constantly vary the theoretically desirable setting of timing switch 68. To prevent actual exposure time from drifting significantly from the pre-setting of timing switch 68, there may be provided a divider control component 83 having as an input factor the rotational speed of the drive for the pull roll 72 and as another input factor a value proportional to the height of the roll 40 within the treating chamber 15. The output of the divider control component 83 is a DC. signal proportional to web velocity (rotational rate of pull roll 72) divided by the height of the dancer roll 40 in the treating chamber 15. In other words, the output of the component 83 is a measure of exposure time then obtaining on the strip treating line.

The manually adjusted control 69 of the time delay switch 68 shown in FIGURE 1 maybe replaced by a control potentiometer and motor 85 supplied by the output of the component 83, through a line 84 so that the time interval for which the switch 68 is set is continuously reset to the exposure time then instantaneously obtaining on the strip processing line so long as the connection through the line 84 is established.

Another feedback circuit to prevent cumulative errors may be provided in the form of a DC. tachometer bridge 90 for sensing the difference in rotational speed of the pull roll 72 and the reference rotational velocity imparted to the differential 50 by the motor 29. This difference may be signaled through an output line 91 to a smaller control potentiometer, motor and angular-position-adjusting-linkage all indicated by the reference numeral. 92 and located between the shaft 62 and the rheostat control arm 30. With this arrangement, any cumulative errors in indicated reference velocity input as supplied by the motor 29 will be corrected by slight adjustment of the angular position of rheostat control arm 30 so long as the connection through the line 91 is established.

Switches 87 and 97 may be inserted respectively in the lines 84 and 91 and may be tied to the switch 67 in the line 66 in such a manner that when the switch 67 is closed,

the switches 87 and 97 are opened Thus, when the switch 67 is closed as at the beginning of a strip velocity transient, the feedback controls of the components 83 and 90 are deactivated temporarily and for the duration of the strip velocity transient and until such time as the switch 67 is subsequently reopened.

It will be understood that within the treating chamber 15, the dancer roll means may comprise a plurality of rolls moving together rather than the single roll 40, and the movement of guide rolls 41 may be increased to provide for additional reaches into the oven in addition to the two illustrated. This would have the result of increasing the mechanical advantage of the strip or web with respect to the linkage 43. In the illustrated apparatus, with the single dancer roll 40, the slaving relationship of dancer rolls to strip velocity transients as above discussed contemplate a proportion of 2:1 between strip acceleration and dancer roll acceleration, respectively, and also between departure of strip velocity from constant velocity and amount of dancer roll velocity, such proportions applying during the shorter of exposure time or strip velocity transient time, as previously described. It will be evident, however, that when the mechanical advantage of the strip 10 with respect to the linkage 43 is increased as by increasing the number of dancer rolls and reaches within the chamber 15, such proportion of 2:1 will be correspondingly changed. For example, if the dancer roll means comprises two rolls so that there are two incoming and two outgoing reaches of the strip 10, making a total of four reaches within the chamber 15, the abovementioned proportion will be 4:1 rather than 2:1.

It is very desirable to provide a counterbalance roll 35 connected to the linkage 43 in a manner similar to the dancer roll 40, but for movement in directions opposite to the movement of the roll 40. This roll 35 counterbalances the tension on the dancer roll 40 and also frees the remainder of the line downstream thereof from experiencing anything other than the velocity transients imposed on the pull stand 14.

In a significant aspect of the invention, it is to be noted that the dancer roll 40 is capable of being lowered to a point outside the treating chamber 15. For emergency shut-down applications with the motor 55 set for a sufficiently high acceleration and with the switches 61 and 64 correspondingly set for a very low web transient time, the web may be very quickly removed from the treating chamber while maintaining uniformity of treatment from increment to increment thereof during such removal and upon subsequent re-starting of the line. The invention is not restricted to the slavish imitation of each and every one of the details described above 8 which have been set forth merely by Way of example with the intent of most clearly setting forth the teaching of the invention. Obviously devices may be provided which change, eliminate or add certain specific details without departing from the invention.

What is claimed is:

1. In continuous and semi-continuous strip treating apparatus, a treating chamber having port means to receive and discharge strip material to be treated within the chamber for a given exposure time, variable speed drive means for said strip, first roll means mounted for translation within the chamber, roll means outside the chamber to guide strip material into an incoming reach leading to said first roll means and away from an outgoing reach leading away from said first roll means, said first roll means being translatable in a path to vary the length of strip material within the treating chamber, such length being increased when said first roll means moves in a first direction along said path and such length being decreased when said first roll means moves in an opposite second direction along said path, means responsive to imposition of positive and negative acceleration on said variable speed drive means for said strip, means controlled by said responsive means for translating said first roll means in said first and second directions as functions, respectively, of positive and negative acceleration imposed on said variable speed drive means for said strip, said responsive means and controlled means together including means for increasing the translation velocity of said first roll means as a direct proportion of departures of strip velocity from the strip velocity prior to the transient until there has elapsed following initiation of strip acceleration the shorter of 1) said given exposure time and (2) the time during which the strip accelerates, and for then continuing translation of said first roll means at constant translation velocity until the longer of said two times expires and then decreasing the translation velocity of said first roll means as a function of time symmetrical to the time-function of said increase in translation velocity of said first roll means.

2. In continuous and semi-continuous strip treating apparatus, a treating chamber having port means to receive and discharge strip material to be treated within the chamber for a given exposure time, variable speed drive means for said strip, first roll means mounted for translation over a continuous range within the chamber and to a point outside the chamber, roll means outside the chamber to guide strip material into an incoming reach leading to said first roll means and away from an outgoing reach leading away from said first roll means, said first roll means being translatable in a path to vary the length of strip material within the treating chamber through a continuous range starting from zero, such length being increased when said first roll means moves in a first direction along said path and such length being decreased when said first roll means moves in an opposite seoond direction along said path, means responsive to imposition of positive and negative acceleration on said variable speed drive means for said strip, means controlled by said responsive means for translating said first roll means in said first and second directions as functions, respectively, of positive and negative acceleration imposedon said variable speed drive means for said strip, said responsive means and controlled means together includiing means for increasing the translation velocity of said first roll means as a direct proportion of departures of strip velocity from the strip velocity prior to the transient until there has elapsed following initiation of strip acceleration the shorter of (1) said given exposure time and (2) the time during which the strip accelerates, and for then continuing translation of said first roll means at constant translation velocity until the longer of said two times expires and then decreasing the translation velocity of said first roll means as a func- 9 tion of time symmetrical to the time-function of said increase in translation velocity of said first roll means.

3. In continuous and semi-continuous strip treating apparatus, a treating chamber having port means to receive and discharge strip material to be treated within the chamber for a given exposure time, variable speed drive means for said strip, a dancer roll mounted for translation within the chamber, roll means outside the chamber to guide strip material into an incoming reach leading to said dancer roll and away from an outgoing reach leading away from said dancer roll, said dancer roll being translatable in a path to vary the length of strip material within the treating chamber, such length being increased when said dancer roll moves in a first direction along said path and such length being decreased when said dancer roll moves in an opposite second direction along said path, means responsive to imposition of positive and negative acceleration on said variable speed drive means for said strip, means controlled by said responsive means for translating said dancer roll in said first and second directions as functions, respectively, of positive and negative acceleration imposed on said variable speed drive means for said strip, said responsive means and controlled means together including means for increasing the translation velocity of said dancer roll as a direct proportion of departures of strip velocity from the strip velocity prior to the transient until there has elapsed following initiation of strip acceleration the shorter of (1) said given exposure time and (2) the time during which the strip accelerates, and for then continuing dancer roll translation at constant translation velocity until the longer of said two times expires and then decreasing the translation velocity of said dancer roll as a function of time symmetrical to the time-function of said increase in translation velocity of said dancer roll.

4. In continuous and semi-continuous strip treating apparatus, a treating chamber having port means to receive and discharge strip material to be treated Within the chamber for a given exposure time, variable speed drive means for said strip, a dancer roll mounted for translation over a continuous range within the chamber :and to a point outside the chamber, roll means outside the chamber to guide strip material into an incoming reach leading to said dancer roll and away from an outgoing reach leading away from said dancer roll, said dancer roll being translatable in a path to vary the length of strip material within the treating chamber through a continuous range starting from zero, such length being increased when said dancer roll moves in a first direction along said path and such length being decreased when said dancer roll moves an opposite second direction along said path, means responsive to imposition of positive and negative acceleration on said variable speed drive means for said strip, means controlled by said responsive means for translating said dancer roll in said first and second directions as functions, respectively, of positive and negative acceleration imposed on said variable speed drive means for said strip, said responsive means and controlled means together including means for increasing the translation velocity of said dancer roll as a direct proportion of departures of strip velocity from the strip velocity prior to the transient until there has elapsed following initiation of strip acceleration the shorter of (1) said given exposure time and (2) the time during which the strip accelerates, and for then continuing dancer roll translation at constant translation velocity until the longer of said two times expires and then decreasing the translation velocity of said dancer roll as a function of time symmetrical to the time-function of said increase in translation velocity of said dancer roll.

5. In continuous and semi-continuous strip treating apparatus, a treating chamber having port means to receive and discharge strip material to be treated within the chamber for a desired exposure time, variable speed drive means for said strip, first roll means mounted for 10 translation within the chamber, roll means outside the chamber to guide strip material into an incoming reach leading to said first roll means and away from an outgoing reach leading away from said first roll means, said first roll means being translatable in a path to vary the length of strip material within the treating chamber, speed reference means normally referable to strip velocity, controlled means for responsively varying translation velocity-of said first roll means in said path with reference to the amount and sign of departure of strip velocity from reference velocities indicated by said speed reference means and a direct proportion of such departure, means for delaying variation of indicated reference velocity of said speed reference means following initiation of line velocity changes, such delay being for an interval equal to said strip exposure time, and for then varying reference velocity as a time-function reversely profiled with respect to that of said departure of strip velocity.

6. In continuous and semi-continuous stn'p treating apparatus, a treating chamber having port means to receive and discharge strip material to be treated within the chamber for a desired exposure time, variable speed drive means for said strip, first roll means mounted for translation over a continuous range the chamber and to a point outside the chamber, roll means outside the chamber to guide strip material into an incoming reach leading to said first roll means and away from an outgoing reach leading away from said first roll means, said first roll means being translatable in a path to vary the length of strip material within the treating chamber, speed reference means normally referable to strip velocity, controlled nieans for responsively varying translation velocity of said first roll means in said path with reference to the amount and sign of departure of strip velocity from reference velocities indicated by said speed reference means and as a direct proportion of such departure, means for delaying variation of indicated reference velocity of said speed reference means following initiation of line velocity changes, such delay being for an interval equal to said strip exposure time, and for then varying reference velocity as a time-function reversely profiled with respect to that of said departure of strip velocity.

7. In continuous and semi-continuous strip treating apparatus, a treating chamber having port means to receive and discharge strip material to be treated the chamber for a desired exposure time, variable speed drive means for said strip, a dancer roll mounted for translation within the chamber, roll means outside the chamber to guide strip material, into an incoming reach leading to said dancer roll and away from an outgoing reach leading away from said dancer roll, said dancer roll being translatable in a path to vary the length of strip material within the treating chamber, speed reference means normally referable to strip velocity, controlled means for responsively varying translation velocity of said dancer roll in said path with reference to the amount and sign of departure of strip velocity from reference velocities indicated by said speed reference means and as a direct proportion of such departure, means for delaying variation of indicated reference velocity of said speed reference means following initiation of line velocity changes, such delay being for an interval equal to said strip exposure'time, and for then varying reference velocity as a time-function reversely profiled with respect to that of said departure of strip velocity.

8. In continuous and semi-continuous strip treating apparatus, a treating chamber having port means to receive and discharge strip material to be treated within the chamber for a desired exposure time, variable speed drive means for said strip, a dancer roll'mounted for translation over a continuous range within the chamber and to a point outside the chamber, roll means outside the chamber to guide strip material into an incoming reach leading to said dancer roll and away from an outgoing reach leading away from said dancer roll, said 1 l dancer roll being translatable in a path to vary the length of strip material within the treating chamber, speed reference means normally referable to strip velocity, controlled means for responsively varying translation velocity of said dancer roll in said path with reference to the amount and sign of departure of strip velocity from reference velocities indicated by said speed reference means and as a direct proportion of such departure, means for delaying variation of indicated reference velocity of said speed reference means following initiation of line velocity 10 12 changes, such delay being for an interval equal to said strip exposure time, and for then varying reference velocity as a time-function reversely profiled with respect to that of said departure of strip velocity.

References Cited in the tile of this patent UNITED STATES PATENTS 1,673,521 Maas June 1 2, 1928 2,837,834 Alexeff et a1 June 19, 1958 2,998,175 Topping Aug. 29, 1961 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No $045,360 July .24 1962 Alexander" V. Alexeff et a1.

corrected below Column 10 line 12, after "and" insert as Signed and sealed this 30th day of October 1962.

l (SEAL) Atteat:

ERNEST W. SWIDER --DAVID L. LADD Attesting Officer Commissioner of Patents 

